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Latest News
Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
A. Kumar, M.Z. Youssef, Y. Ikeda, C. Konno, Y. Oyama
Fusion Science and Technology | Volume 19 | Number 3 | May 1991 | Pages 1859-1866
Neutronic | Proceedings of the Ninth Topical Meeting on the Technology of Fusion Energy (Oak Brook, Illinois, October 7-11, 1990) | doi.org/10.13182/FST91-A29614
Articles are hosted by Taylor and Francis Online.
The recently concluded phase IIIA experiments of the USDOE/JAERI collaborative program mark a watershed in that a D-T line source was simulated by moving detectors/annular Li2O blanket-assembly with respect to a stationary point source. Three experiments were conducted in three stages during this phase: (i) source characterization (step-mode, 10 cm step, 9h47m duration, 3 sample locations), (ii) in-situ short irradiation (stationary assembly, 30m duration, 2 sample locations), (iii) in-situ long irradiation (continuous-mode, 9h51m duration, 3 sample locations). The sample-materials included: Fe, Ni, Mo, SS316, W, Ta, Zr, Al, Sn, Ag, Pb, Zn, Nb, Ti, V, Co and In. The sample locations inside the phase IIIA assembly were so chosen as to monitor (a) the impact of lack of line source simulation on decay γ-radioactivity, (b) the influence of SS304 first wall, (c) the role of neutron spectral degradation in the annular Li2O fusion blanket assembly. The experimental results demonstrate that: (1) continuous-mode operation provides better simulation of line source even for radioactive products of half lives as low as ∼10 min, (2) the decay γ-emission rates generally drop as one moves away from the center of simulated line source (length=2 meters), (3) the presence of surrounding annular blanket leads to larger enhancements in the γ-emission rates ascribable to reactions induced by energy-degraded neutrons. The analysis of these measurements shows up discrepancies for most of the materials. DKRICF lacks decay data for many isotopes. For example, decay data is absent for Y, 186Ta, 187W, and 181W. For Zr, 91mY contribution is severely underestimated. Severe underestimation hits Zn and Sn (especially 117mSn and 111In). REAC2 related more important observations can be summarized as follows: For Mo, 91Mo is strongly overestimated and 101Mo, 99Mo, 98mNb, 97Nb, 93mNb are underestimated. For Zr, 89m+gZr, 90mY and 91mY are strongly overestimated. For W, 179mW yields abnormally large contribution for both short and long cooling times. The data base for Zn needs complete overhaul as for some isotopes there is strong overestimation (65Ni, 67Cu and 69Zn), while yet for others, there is severe underestimation (69mZn, 65Zn and 64Cu).
